Identifying geochemical anomalies and spatial distribution of gold and associated elements in the Zuru Schist Belt, northwest Nigeria

Abstract

The Zuru Schist Belt is one of the gold-bearing schist belts in northwestern Nigeria. The gold mineralisation is mainly associated with NE-trending shear zones and is hosted in veins of quartz, quartz-tourmaline and quartz-feldspar. In this study, the spatial pattern of gold and associated elements was identified and delineated through statistical analysis of trace element geochemical data. Statistical analyses including spearman correlation, principal component analysis and hierarchical cluster analysis were applied on the geochemical data to decipher and interpret multi-element association related with gold mineralisation. Spearman correlation revealed significant positive correlation amongst Co, Mn, Fe, V, Ni and Zn (>0.70), while Au has moderate correlation with Ag, Bi and Cu (>0.30). Based on principal component analysis and hierarchical cluster analysis, three element associations can be recognised: (a) Zn-Ni-Co-Mn-Fe-V, (b) Au-Ag-Bi-Pb and (c) Zn-U-Th-Sr-La-Ba. The first two multi-element associations are related to gold mineralisation. The multi-element association of Zn-Ni-Co-Mn-Fe-V signifies lithogenic factor and associated hydrothermal alteration, while Au-Ag-Bi-Pb is indicative of gold mineralisation. The combination of Au and associated elements (Ag, Bi and Pb), which was achieved through the use of uni-element thresholds (median+2 median absolute deviation) in multi-element halo technique, enabled the mapping of multi-element geochemical anomaly. The uni- and multi-element geochemical anomaly maps show geochemical anomalies in the northern, central and southern parts of the area. These anomalies, largely restricted to metasedimentary rocks notably foliated quartzite, schist, and phyllite, represent where further exploration should be focused with more attention particularly in the northern part where higher concentration than previously reported was observed.